Excessive alcohol consumption is a prerequisite for the development of alcohol dependence. Therefore, it is important to identify molecular targets affected by high alcohol intake in order to understand the mechanisms of alcoholism progression, which mediate the switch from controlled alcohol consumption to alcohol abuse and alcohol dependence. The dopamine (DA) neurons of the ventral tegmental area (VTA)send projections to several forebrain regions, where dopamine release has been associated with reward learning and craving. Recent studies that used retrograde labeling showed that VTA DA neurons with different projection targets have different electrophysiological and neurochemica'l properties (Ford et al., 2006; Margolis et al., 2006). These studies highlight the importance of 1. Fine mapping of neuronal circuits involved in regulation of motive/reward behaviors. 2. Identifying cell-type- and circuit-specific molecular profiles and molecular markers that underlie cellular properties of different neuronal populations and play a major role in neuronal plasticity. Here, we propose to use an animal model of binge drinking to study effects of alcohol on gene expression and cellular properties in two populations of VTA DA neurons one projecting to the medial Prefrontal Cortex (mPFC) and the other to the Nucleus Accumbens (NAc) shell (brain regions involved in regulation of alcohol consumption). Alcohol-preferring FVB x C57BL/6 F1 hybrid mice will drink intoxicating amounts of alcohol in a binge fashion for several days. VTA neurons will be retrogradely labeled using brain microinjections of fluorescent tracer to the mPFC or the NAc shell. Labeled neurons will be dissected using laser capture microdissection (LCM) and characterized using DNA microarrays, qRT-PCR and patch-clamp recordings in brain slices. The overall hypothesis is that different neuronal populations can be distinguished by their individual patterns of gene expression and by their transcriptional responses to alcohol, which may correlate with cell physiology. This study will identify cell type - specific alcohol-sensitive molecular targets, which will open an opportunity to develop means to affect neuronal behavior in a circuit - specific manner. The long term goal of this research is to determine molecular mechanisms of cellular adaptation to alcohol in individual neuronal populations of the neurocircuits that mediate alcohol actions. This knowledge may be used to develop drugs for treatment of alcoholism.